Propulsion system with a continuously variable transmission

ABSTRACT

One disclosed embodiment relates to a propulsion system for a machine. The propulsion system may include a prime mover operatively connected through a continuously variable transmission to a propulsion device. The propulsion system may also include propulsion-system controls that control an operating parameter of the continuously variable transmission, which may include adjusting the operating parameter based on operator input. Controlling the operating parameter may also include determining an adjustment limit for the operating parameter based on one or more operating conditions and applying the adjustment limit to the operating parameter to modify at least one of acceleration and jerk of the machine based on the one or more operating conditions.

TECHNICAL FIELD

The present disclosure relates to propulsion systems for mobile machinesand, more particularly, to propulsion systems having continuouslyvariable transmissions.

BACKGROUND

Many mobile machines include a propulsion system with a multiple-ratiotransmission operable to transmit power from a prime mover (such as anengine) to propulsion devices (such as wheels) at any of a plurality ofoptional drive ratios. Some multiple-ratio transmissions have astep-change configuration, meaning that the transmission has a finiteset of discrete drive ratios at which it can transmit power. Othermultiple-ratio transmissions, known as continuously variabletransmissions, have a configuration allowing adjustment of thetransmission's drive ratio through a continuous range. The advantagesassociated with continuously variable transmissions include thedecoupling of the transmission input speed from the transmission outputspeed and the ability to rapidly adjust the drive ratio, the outputspeed, and the amount of torque output by the transmission. This mayhelp the propulsion system meet operator requests for abrupt changes inthe travel speed of the mobile machine. Unfortunately, the rapidadjustment capability of continuously variable transmissions creates thepossibility of undesirably abrupt adjustment in response to operatorinputs.

U.S. Pat. No. 5,931,884 to Ochiai (“the '884 patent”) discloses a methodof controlling a continuously variable transmission, includingcalculating an upper limit for the rate at which the drive ratio of thecontinuously variable transmission changes. The '884 patent expressesconcerns that some control strategies for continuously variabletransmissions may produce undesirable deceleration in particularcircumstances by changing the drive ratio of the continuously variabletransmission too rapidly and thereby causing negative torque at theoutput shaft of the continuously variable transmission. In order toaddress this concern, the control method of the '884 patent involvescalculating the maximum rate at which the drive ratio of thecontinuously variable transmission can change without causing its outputtorque to drop to or below zero. The control method of the '884 patentimposes this calculated maximum rate as a limit on the adjustment of thedrive ratio of the continuously variable transmission, therebypreventing deceleration due to rapid adjustment of the continuouslyvariable transmission.

Although the control method of the '884 patent involves calculating andimposing a limit on the rate of change of the drive ratio of thecontinuously variable transmission, certain disadvantages persist. Forexample, the adjustment limit imposed by the control method of the '884patent limits acceleration in the same manner in all circumstances.Thus, the '884 patent fails to recognize that the desirable limits onacceleration may vary depending on various operating conditions.

The propulsion system and control methods of the present disclosuresolve one or more of the problems set forth above.

SUMMARY OF THE INVENTION

One disclosed embodiment relates to a propulsion system for a machine.The propulsion system may include a prime mover operatively connectedthrough a continuously variable transmission to a propulsion device. Thepropulsion system may also include propulsion-system controls thatcontrol an operating parameter of the continuously variabletransmission, which may include adjusting the operating parameter basedon operator input. Controlling the operating parameter may also includedetermining an adjustment limit for the operating parameter based on oneor more operating conditions and applying the adjustment limit to theoperating parameter to modify at least one of acceleration and jerk ofthe machine based on the one or more operating conditions.

Another embodiment relates to a method of propelling a machine with apropulsion system. The propulsion system may include a prime moveroperatively connected through a continuously variable transmission to apropulsion device and propulsion-system controls. The machine may alsohave one or more other machine systems. The method may includetransmitting power from the prime mover to the propulsion device withthe continuously variable transmission while controlling a firstoperating parameter of the continuously variable transmission with thepropulsion-system controls. Controlling the first operating parameterwith the propulsion-system controls may include adjusting the operatingparameter based on operator input. Controlling the first operatingparameter with the propulsion-system controls may also includedetermining an adjustment limit for the first operating parameter basedon one or more second operating parameters of the one or more othersystems of the machine. Additionally, controlling the first operatingparameter with the propulsion-system controls may include applying theadjustment limit to the first operating parameter.

A further disclosed embodiment relates to a propulsion system for amachine. The propulsion system may include a prime mover operativelyconnected through a continuously variable transmission to a propulsiondevice. Additionally, the propulsion system may includepropulsion-system controls that control acceleration and jerk of themachine at least in part by controlling an operating parameter of thecontinuously variable transmission. Controlling the operating parameterof the continuously variable transmission may include adjusting theoperating parameter based on operator input. Additionally, controllingthe operating parameter may include limiting at least one of theacceleration and jerk of themachine by determining an adjustment limitfor the operating parameter and applying the adjustment limit to theoperating parameter, the adjustment limit being determined based on atleast one of the direction of travel of the machine and the direction oftravel requested by an operator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of a machine having one embodimentof a propulsion system according to the present disclosure; and

FIG. 2 is a flow chart illustrating one embodiment of a control methodaccording to the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates a mobile machine 10 having one embodiment of apropulsion system 12 according to the present disclosure. In addition topropulsion system 12, mobile machine 10 may have various other systems,including, but not limited to, a steering system 14 and an implement 16.

Propulsion system 12 may include a prime mover 18, propulsion devices20, a drive train 22, and propulsion-system controls 24. Prime mover 18may be any type of component operable to provide power for propellingmobile machine 10. For example, prime mover 18 may be a diesel engine, agasoline engine, a gaseous-fuel-driven engine, or a turbine engine.Prime mover 18 may have a rotary output member 26 for supplying rotarymechanical power. Prime mover 18 may also include prime-mover controls44. Prime-mover controls 44 may include any component or componentsoperable to control one or more aspects of the operation of prime mover18. In some embodiments, prime-mover controls 44 may include aprime-mover controller 46 operatively connected to various sensorsand/or actuators (not shown) for monitoring and controlling prime mover18. Prime-mover controller 46 may include one or more processors (notshown) and one or more memory devices (not shown).

Propulsion devices 20 may include any type of components operable topropel mobile machine 10 by receiving power from one or more othercomponents of propulsion system 12 and apply that power to theenvironment surrounding mobile machine 10. For example, as shown in FIG.1, propulsion devices 20 may include wheels. Propulsion devices 20 mayalso include various other types of devices in addition to, or in placeof, wheels, including, but not limited to, track units and/orpropellers.

Drive train 22 may include any component or components operable totransfer power from prime mover 18 to propulsion devices 20 to propelmobile machine 10. For example, drive train 22 may include acontinuously variable transmission 28, a drive shaft 30, a differentialunit 32, and axle shafts 34 connected between prime mover 18 andpropulsion devices 20. Continuously variable transmission 28 may have arotary input member 36 and a rotary output member 38. Rotary inputmember 36 may connect directly or indirectly to rotary output member 26of prime mover 18. Drive shaft 30, differential unit 32, and axle shafts34 may connect rotary output member 38 to propulsion devices 20.

Continuously variable transmission 28 may have any configuration thatallows transferring power between rotary input member 36 and rotaryoutput member 38 while varying the ratio of the speed of rotary inputmember 36 to the speed of rotary output member 38 through a continuousrange. In some embodiments, continuously variable transmission 28 mayhave a mechanical power-transfer path 40 and a hydraulic power-transferpath 42 connected in parallel between rotary input member 36 and rotaryoutput member 38. Mechanical power-transfer path 40 may include aplanetary gear set 48 connected between rotary input member 36 androtary output member 38. Rotary input member 36 may, for example,connect directly or indirectly to the sun gear of planetary gear set 48,and the planet carrier of planetary gear set 48 may connect directly orindirectly to rotary output member 38.

Hydraulic power-transfer path 42 may include a hydraulic pump 50, ahydraulic motor 52, and a fluid-transfer system 56 for deliveringhydraulic fluid pumped by hydraulic pump 50 to hydraulic motor 52.Fluid-transfer system 56 may include various conduits, valves,reservoirs, and/or other known hydraulics components. Hydraulic pump 50may connect to rotary input member 36. Hydraulic motor 52 may, forexample, connect to the ring gear of planetary gear set 48. Thisconnection of rotary input member 36, hydraulic motor 52, and rotaryoutput member 38 to planetary gear set 48 makes the speed of rotaryinput member 36, the speed of hydraulic motor 52, and the speed ofrotary output member 38 interdependent.

Continuously variable transmission 28 may also include a reversermechanism 80 connected between planetary gear set 48 and rotary outputmember 38. Reverser mechanism 80 may have one operating state thatresults in rotary output member 38 rotating in the same direction asrotary input member 36, and reverser mechanism 80 may have anotheroperating state that results in rotary output member 38 rotating in adirection opposite rotary input member 36. Thus, one operating state ofreverser mechanism 80 may allow propulsion of mobile machine 10 in aforward direction 72, and another operating state of reverser mechanism80 may allow propulsion of mobile machine 10 in a reverse direction 74.Reverser mechanism 80 may have various combinations of power-transfercomponents, including, but not limited to, gears, pulleys, sprockets,chains, and/or clutches arranged in various manners.

Continuously variable transmission 28 may also include transmissioncontrols 54. Transmission controls 54 may include any component orcomponents operable to control one or more parameters of the operationof continuously variable transmission 28. Transmission controls 54 may,for example, include a transmission controller 58 operatively connectedto various components of continuously variable transmission 28.Transmission controller 58 may include one or more processors (notshown) and one or more memory devices (not shown). Transmissioncontroller 58 may be operatively connected to one or more components ofhydraulic power-transfer path 42 in a manner enabling transmissioncontroller 58 to control the speed and power output of hydraulic motor52. Transmission controller 58 may, for example, be operativelyconnected to hydraulic pump 50 and hydraulic motor 52 in a mannerenabling transmission controller 58 to control the displacement ofhydraulic pump 50 and the displacement of hydraulic motor 52. Bycontrolling the operating speed and power output of hydraulic motor 52,transmission controller 58 may control the ratio of the speed of rotaryinput member 36 to the speed of rotary output member 38, as well as thespeed and torque output of rotary output member 38. Transmissioncontroller 58 may also be operatively connected to reverser mechanism80, such that transmission controller 58 may control whether rotaryoutput member 38 rotates in the same direction as, or opposite to,rotary input member 36.

Propulsion-system controls 24 may include prime-mover controls 44,transmission controls 54, a master controller 60, and one or moreoperator-input devices of an operator interface 62 of mobile machine 10.Master controller 60 may include one or more processors (not shown) andone or more memory devices (not shown). Master controller 60 may receiveinformation from various sources.

In some embodiments, master controller 60 may receive input from theoperator-input devices of propulsion-system controls 24. Theseoperator-input devices may include, for example, aFORWARD/NEUTRAL/REVERSE selector 66, an accelerator pedal 68, and adecelerator pedal 70. An operator of mobile machine 10 may select the“FORWARD” operating state of FORWARD/NEUTRAL/REVERSE selector 66 torequest propulsion of mobile machine 10 in forward direction 72.Conversely, the operator may select the “REVERSE” operating state ofFORWARD/NEUTRAL/REVERSE selector 66 to request propulsion of mobilemachine 10 in reverse direction 74. Alternatively, the operator mayselect the “NEUTRAL” operating state of FORWARD/NEUTRAL/REVERSE selector66 to request that propulsion system 12 not propel mobile machine 10 ineither forward direction 72 or reverse direction 74.

With the FORWARD/NEUTRAL/REVERSE selector 66 in its FORWARD or REVERSEoperating state, accelerator pedal 68 and decelerator pedal 70 may allowthe operator to indicate how rapidly he desires propulsion system 12 topropel mobile machine 10 in the chosen direction. Accelerator pedal 68may generate a signal 76 indicating how far the operator has depressedit from its default position. Similarly, decelerator pedal 70 mygenerate a signal 78 indicating how far the operator has depressed itfrom its default position. Generally, master controller 60 may interpretincreased depression of accelerator pedal 68 as a request for increasedspeed in the chosen direction and increased depression of deceleratorpedal 70 as a request for decreased speed in the chosen direction. Insome embodiments, master controller 60 may consider signals 76, 78collectively as the indication of the propulsion speed desired by theoperator. In such embodiments, master controller 60 may consider anydepression of decelerator pedal 70 as at least partially offsetting anydepression of accelerator pedal 68 and vice versa, with the relationshipbetween signals 76, 78 defining the desired propulsion speed.

In addition to operator-input devices, various other components and/orsystems may provide information to master controller 60. For example, aspeed/direction sensor 82 may provide master controller 60 a signalindicating the travel speed of mobile machine 10, as well as whethermobile machine 10 is traveling in forward direction 72 or in reversedirection 74. Master controller 60 may also receive signals from variousother sensors (not shown), including, but not limited to, otherspeed/direction sensors, position sensors, pressure sensors, and/ortemperature sensors.

Master controller 60 may also be operatively connected to prime-movercontrols 44 and transmission controls 54. For example, master controller60 may be communicatively linked to prime-mover controller 46 ofprime-mover controls 44, as well as to transmission controller 58 oftransmission controls 54. This may allow master controller 60 tocoordinate control of prime mover 18 and continuously variabletransmission 28 by receiving information from and sending controlcommands to prime-mover controller 46 and transmission controller 58.

Propulsion system 12 is not limited to the configuration shown inFIG. 1. For example, continuously variable transmission 28 may have adifferent configuration. Continuously variable transmission 28 mayinclude components not shown in FIG. 1, and/or continuously variabletransmission 28 may omit one or more of the components shown in FIG. 1.In some embodiments, continuously variable transmission 28 may includeprovisions for discrete changes in the drive ratio within variousportions of mechanical power-transfer path 40 and/or in other portionsof continuously variable transmission 28. Additionally, in someembodiments, in place of hydraulic power-transfer path 42, continuouslyvariable transmission 28 may have an electrical power-transfer pathparallel with mechanical power-transfer path 40. Such an embodiment ofcontinuously variable transmission 28 may include an electric generator,an electric motor, and an electrical power-transfer circuit in place ofhydraulic pump 50, hydraulic motor 52, and fluid-transfer system 56,respectively.

Additionally, in some embodiments, continuously variable transmission 28may not have parallel power-transfer paths. For example, continuouslyvariable transmission 28 may have a single mechanical power-transferpath. Alternatively, continuously variable transmission 28 may be aconventional hydrostatic transmission. Similarly, continuously variabletransmission 28 may include only an electrical power-transfer path thatincludes an electric generator connected directly or indirectly torotary input member 36 and an electric motor connected directly orindirectly to rotary output member 38.

Drive train 22 may also have continuously variable transmission 28connected between rotary output member 26 of prime mover 18 andpropulsion devices 20 differently than shown in FIG. 1. For example,drive train 22 may include various additional components connectedbetween rotary input member 36 of continuously variable transmission 28and rotary output member 26 of prime mover 18, including, but notlimited to, one or more clutches, fluid couplers, gears, pulleys, belts,sprockets, and chains. Similarly, drive train 22 may have additionalpower-transfer components connected between rotary output member 38 ofcontinuously variable transmission 28 and propulsion devices 20, and/ordrive train 22 may omit one or more of drive shaft 30, differential unit32, and axle shafts 34.

Additionally, propulsion-system controls 24 may have a differentconfiguration. For example, in combination with, or in place of,FORWARD/NEUTRAL/REVERSE selector 66, accelerator pedal 68, anddecelerator pedal 70, propulsion-system controls 24 may include variousother operator-input devices with which an operator may indicate one ormore aspects of how the operator desires propulsion system 12 to propelmobile machine 10. Additionally, propulsion-system controls 24 may omitone or more of prime-mover controller 46, transmission controller 58,and master controller 60. Furthermore, propulsion-system controls 24 mayinclude various other types of control components, such as hardwiredcontrol circuits, in addition to, or in place of, one or more ofprime-mover controller 46, transmission controller 58, and mastercontroller 60.

Steering system 14 may include any component or components operable tocontrol whether, in what direction, and how sharply mobile machine 10turns while traveling in forward direction 72 or reverse direction 74.For example, steering system 14 may include steering actuators 84 andsteering-system controls 86. Under the control of steering-systemcontrols 86, steering actuators 84 may interact with other components ofmobile machine 10 in various manners to control whether, in whatdirection, and how sharply mobile machine 10 turns. In some embodiments,steering actuators 84 may control the direction of front wheels 88 ofmobile machine 10 relative to propulsion devices 20.

Steering-system controls 86 may, for example, include actuator controls90, a steering-input device 92 of operator interface 62, and mastercontroller 60. Actuator controls 90 may include any component orcomponents operable to control the operation of steering actuators 84.Steering-input device 92 may include any component or components that anoperator may use to indicate how the operator wishes to steer mobilemachine 10. For example, steering-input device 92 may include ajoystick. Master controller 60 may be operatively connected tosteering-input device 92 and actuator controls 90. Accordingly, mastercontroller 60 may indirectly control steering actuators 84 based oninformation from steering-input device 92.

Steering system 14 is not limited to the configuration shown in FIG. 1.Steering system 14 may employ an approach other than controlling thedirection of front wheels 88 to turn mobile machine 10. For example,steering system 14 may steer mobile machine 10 in a skid-steer manner.Additionally, steering system 14 may have steering-input device 92connected directly to actuator controls 90, rather than having mastercontroller 60 control actuator controls 90 based on information fromsteering-input device 92. Furthermore, in some embodiments, steeringsystem 14 may omit steering actuators 84 and actuator controls 90,requiring the operator to provide the force to steer mobile machine 10.

Implement 16 may be any type of device configured to perform one or moretasks other than propelling mobile machine 10. For example, as shown inFIG. 1, implement 16 may be a front-end loader. Implement 16 may includeone or more actuators 94 that power it, and mobile machine 10 mayinclude implement controls 96 for controlling actuators 94 to controlimplement 16. Implement controls 96 may include an implement-inputdevice 98 of operator interface 62, actuator controls 100, and mastercontroller 60. Implement-input device 98 may include any component orcomponents that an operator can use to indicate how the operator wantsto operate implement 16, including, but not limited to, one or morehandles, pedals, and/or buttons. Actuator controls 100 may include anycomponent or components operable to control actuators 94. Mastercontroller 60 may be operatively connected to implement-input device 98and actuator controls 100, so that master controller 60 may controlactuators 94 through actuator controls 100 in order to operate implement16 in accordance with input from implement-input device 98.

Implement 16 and implement controls 96 are not limited to theconfiguration shown in FIG. 1. Implement 16 may be, for example, a typeof implement other than a front-end loader, such as an excavating tool,a hoist, a demolition tool, or the like. Implement controls 96 may haveimplement-input device 98 connected directly to actuator controls 100,rather than employing master controller 60 to control actuator controls100 based on information from implement-input device 98. Additionally,implement controls 96 may include other implement-input devices (notshown) in addition to implement-input device 98.

Mobile machine 10 is not limited to the configuration shown in FIG. 1.For example, mobile machine 10 may have propulsion system 12, steeringsystem 14, and implement 16 arranged in different manners. Mobilemachine 10 may also include various systems not shown in FIG. 1. In someembodiments, mobile machine 10 may include other implements in additionto implement 16. Alternatively, mobile machine 10 may omit implement 16.Similarly, mobile machine 10 may omit steering system 14.

INDUSTRIAL APPLICABILITY

Propulsion system 12 may have application for propelling any mobilemachine 10. Prime mover 18 may provide power to propel mobile machine 10by rotating rotary input member 36 of continuously variable transmission28 with rotary output member 26. Continuously variable transmission 28may transfer at least a portion of this power from rotary input member36 to rotary output member 38. Propulsion devices 20 may receive thepower output by rotary output member 38 and apply that power to theenvironment around mobile machine 10, thereby propelling mobile machine10.

While propulsion system 12 propels mobile machine 10 in this manner,propulsion-system controls 24 may control the direction and magnitude ofacceleration of mobile machine 10, as well as the jerk of mobile machine10 (the rate of change of the acceleration). To do so, propulsion-systemcontrols 24 may control various operating parameters of propulsionsystem 12, including, but not limited to, one or more operatingparameters of prime mover 18 and/or one or more operating parameters ofcontinuously variable transmission 28. For example, propulsion-systemcontrols 24 may control how much power rotary output member 38 ofcontinuously variable transmission 28 outputs by adjusting the operationof continuously variable transmission 28 and/or prime mover 18 tocontrol the speed and torque output of rotary output member 38.

Generally, propulsion-system controls 24 may control the power thatrotary output member 38 provides (and thus the acceleration and jerk ofmobile machine 10) in accordance with operator inputs. For example, whenthe operator requests an increase or decrease in speed,propulsion-system controls 24 may adjust the torque output of rotaryoutput member 38 by an amount based on the magnitude of the requestedspeed increase or decrease. Similarly, when mobile machine 10 istraveling in forward direction 72 or reverse direction 74 and theoperator manipulates FORWARD/NEUTRAL/REVERSE selector 66 to requestpropulsion in the opposite direction, propulsion-system controls 24 maychange the output torque provided by rotary output member 38. In suchcircumstances, propulsion-system controls 24 may, for example, adjustthe operation of continuously variable transmission 28 and/or primemover 18 to change the direction of the torque output by rotary outputmember 38 to first decelerate mobile machine 10 to a stop and thenaccelerate mobile machine 10 in the newly requested forward direction 72or reverse direction 74. When changing the direction of torque output byrotary output member 38 in response to such an operator-requesteddirectional shift, propulsion-system controls 24 may control themagnitude of the output torque based at least in part on the signals 76,78 from accelerator pedal 68 and decelerator pedal 70.

Propulsion-system controls 24 may, however, impose a limit on adjustmentof the continuously variable transmission 28 and/or prime mover 18 inresponse to operator requests for acceleration, deceleration, anddirectional shifts. By imposing such a limit, propulsion-system controls24 may avoid excessive levels of acceleration and jerk. As explained indetail below, propulsion-system controls 24 may impose this limit in amanner that limits the acceleration and/or jerk of mobile machine 10differently in some circumstances than in other circumstances. By doingso, propulsion-system controls 24 may allow relatively high levels ofacceleration and jerk in circumstances where the operator expects anddesires aggressive response from propulsion system 12, while limitingacceleration and jerk to lower values in circumstances where theoperator does not expect or desire such aggressive operation.

Propulsion-system controls 24 may employ various methods to limitacceleration and/or jerk of mobile machine 10 differently in somecircumstances than in other circumstances. FIG. 2 illustrates oneembodiment of a control method that propulsion-system controls 24 mayuse for this purpose. In this exemplary method, propulsion-systemcontrols 24 may continually monitor for changes in operator inputsrelated to propulsion (step 102). When propulsion-system controls 24detect a change in operator inputs related to propulsion,propulsion-system controls 24 may determine a target adjustment for anoperating parameter of continuously variable transmission 28 based onthe change in the operator inputs (step 104). For example,propulsion-system controls 24 may determine a target adjustment for aparameter of the power output by rotary output member 38 in response tochanged operator inputs relating to propulsion. In some embodiments,propulsion-system controls 24 may determine a target adjustment in thetorque output of rotary output member 38 in response to an operatorrequest for increased acceleration, increased deceleration, and/or adirectional shift.

Simultaneously, propulsion-system controls 24 may determine anadjustment limit for the operating parameter of the continuouslyvariable transmission 28 based on one or more operating conditions (step106). The adjustment limit may be, for example, a limit on the rate ofchange of the operating parameter, such as a limit on the rate of changeof the torque output of rotary output member 38. After calculating thetarget adjustment and the adjustment limit for the operating parameter,propulsion-system controls 24 may determine whether the targetadjustment exceeds the adjustment limit (step 108). If not,propulsion-system controls 24 may adjust the operating parameter by thetarget amount (step 110). On the other hand, if the target adjustmentexceeds the adjustment limit, propulsion-system controls 24 may imposethe adjustment limit and adjust the operating parameter up to theadjustment limit (step 112) instead of implementing the targetadjustment. By limiting the rate of change of the torque output ofrotary output member 38 or some other parameter of the power output byrotary output member 38, propulsion-system controls 24 may limit theacceleration and/or jerk of mobile machine 10. Thus, by determining andapplying the adjustment limit in the manner discussed above,propulsion-system controls 24 may modify the acceleration and/or jerk ofmobile machine 10 based on the one or more operating conditions used todetermine the adjustment limit.

By calculating the adjustment limit based on one or more operatingconditions, propulsion-system controls 24 may tailor the adjustmentlimit and the associated limit on the acceleration and/or jerk of themobile machine 10 to the circumstances at hand. Propulsion-systemcontrols 24 may use various operating conditions to determine theadjustment limit. In some embodiments, propulsion-system controls 24 maydetermine the adjustment limit based at least in part on whether mobilemachine 10 is traveling in forward direction 72 or reverse direction 74.With all other factors being equal, propulsion-system controls 24 mayset the adjustment limit higher if mobile machine 10 is traveling inforward direction 72 than if mobile machine 10 is traveling in reversedirection 74.

Propulsion-system controls 24 may also base the adjustment limit atleast partially on whether the target adjustment of the operatingparameter involves an increase or decrease in the quantity of torqueoutput at rotary output member 38. In some embodiments, all otherfactors being equal, if the target adjustment to the operating parameterinvolves an increase in the quantity of torque output at rotary outputmember 38, propulsion-system controls 24 may set the adjustment limitlower than if the target adjustment to the operating parameter involvesa decrease in the quantity of torque output at rotary output member 38.An operator may find relatively abrupt decreases in the output torque atrotary output member 38 more agreeable than relatively abrupt increasesin the output torque at rotary output member 38.

In some embodiments, to determine the adjustment limit,propulsion-system controls 24 may consider the direction of travel incombination with whether mobile machine 10 is accelerating ordecelerating. In other words, propulsion-system controls 24 may set theadjustment limit dependent on whether mobile machine 10 is (1) travelingin forward direction 72 and accelerating, (2) traveling in forwarddirection 72 and decelerating, (3) traveling in reverse direction 74 andaccelerating, or (4) traveling in reverse direction 74 and decelerating.Propulsion-system controls 24 may set the adjustment limit differentlyfor each of these four different circumstances.

Propulsion-system controls 24 may also set the adjustment limitdependent at least in part on whether the direction of travel requestedby the operator matches the actual direction of travel of mobile machine10. As discussed above, when mobile machine 10 is traveling either inforward direction 72 or reverse direction 74, the operator may changethe operating state of FORWARD/NEUTRAL/REVERSE selector 66 to requestpropulsion in the opposite direction, at which time the requesteddirection of travel generally will not match the actual direction oftravel. When the operator makes such a request for a direction shift,propulsion-system controls 24 may determine the adjustment limitdifferently than when the actual direction of travel of mobile machine10 matches the requested direction of travel. In some embodiments, allother factors being equal, propulsion-system controls 24 may set theadjustment limit higher when the actual direction of travel does notmatch the requested direction of travel than when the actual directionof travel does match the requested direction of travel.

Propulsion-system controls 24 may also determine the adjustment limitbased on the travel speed of mobile machine 10. For example, in someembodiments, all other factors being equal, propulsion-system controls24 may set the adjustment limit lower with increasing travel speed ofmobile machine 10.

Propulsion-system controls 24 may also determine the adjustment limitbased at least in part on one or more operating conditions of one ormore systems other than propulsion system 12. For example,propulsion-system controls 24 may set the adjustment limit based atleast in part on one or more operating parameters of steering system 14,such as an operating parameter indicative of whether and how sharplymobile machine 10 is turning. In some embodiments, all other factorsbeing equal, the more sharply mobile machine 10 is turning, the lowerpropulsion-system controls 24 may set the adjustment limit.Additionally, propulsion-system controls 24 may determine the adjustmentlimit based at least in part on one or more operating conditions ofimplement 16. For example, in embodiments where implement 16 is afront-end loader, propulsion-system controls 24 may set the adjustmentlimit based on how high the operator has raised the bucket thereof.

Propulsion-system controls 24 may use various combinations of thefactors discussed above and/or various other operating conditions todetermine the adjustment limit. In some embodiments, propulsion-systemcontrols 24 may always use the same factors to determine the adjustmentlimit. Alternatively, propulsion-system controls 24 may use one or morefactors only some of the time when determining the adjustment limit.

Methods that propulsion-system controls 24 may use to limit theacceleration and/or jerk of mobile machine 10 differently in differentcircumstances are not limited to the examples discussed above. Forexample, propulsion-system controls 24 may implement differentrelationships between the adjustment limit and the operating conditionsused to determine the adjustment limit. Additionally, propulsion-systemcontrols 24 may limit the acceleration and/or jerk of mobile machine 10by setting a limit on adjustment of an operating parameter ofcontinuously variable transmission 28 other than the torque output byrotary output member 38. Furthermore, in determining and imposing theadjustment limit, propulsion-system controls 24 may perform the actionsshown in FIG. 2 in different orders and/or perform other actions inaddition to, or in place of, the actions shown in FIG. 2.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the disclosed propulsionsystem and control methods without departing from the scope of thedisclosure. Other embodiments of the disclosed propulsion system andcontrol methods will be apparent to those skilled in the art fromconsideration of the specification and practice of the propulsion systemand control method disclosed herein. It is intended that thespecification and examples be considered as exemplary only, with a truescope of the disclosure being indicated by the following claims andtheir equivalents.

1-10. (canceled)
 11. A method of propelling a machine with a propulsionsystem having a prime mover operatively connected through a continuouslyvariable transmission to a propulsion device, propulsion-systemcontrols, and one or more other machine systems, the method comprising:transmitting power from the prime mover to the propulsion device withthe continuously variable transmission while controlling a firstoperating parameter of the continuously variable transmission with thepropulsion-system controls, including adjusting the first operatingparameter based on operator input, determining a magnitude of anadjustment limit for the first operating parameter based on one or moresecond operating parameters of the one or more other systems of themachine, including determining the magnitude of the adjustment limitbased at least in part on whether the machine is travelling in a forwarddirection or in a reverse direction, and applying the adjustment limitto the first operating parameter.
 12. The method of claim 11, wherein:the one or more other systems of the machine include a steering system;and determining the magnitude of the adjustment limit for the operatingparameter based on one or more second operating parameters of the one ormore other systems of the machine includes determining the magnitude ofthe adjustment limit for the operating parameter based on an operatingparameter of the steering system.
 13. The method of claim 11, wherein:the one or more other systems of the machine include an implement; anddetermining the magnitude of the adjustment limit for the operatingparameter based on one or more second operating parameters of the one ormore other systems of the machine includes determining the magnitude ofthe adjustment limit for the operating parameter based on an operatingparameter of the implement.
 14. The method of claim 11, whereindetermining the magnitude of the adjustment limit for the operatingparameter includes determining the magnitude of the adjustment limitbased on one or more third operating parameters of the propulsion systemin addition to the one or more second operating parameters of the one ormore other systems of the machine.
 15. The method of claim 11, whereinthe first operating parameter is a parameter of power that thecontinuously variable transmission outputs.
 16. The method of claim 11,wherein the first operating parameter is an amount of torque that thecontinuously variable transmission outputs.
 17. The method of claim 11,wherein the adjustment limit is a limit on the rate of change of thefirst operating parameter. 18-20. (canceled)
 21. A method of propellinga machine with a propulsion system having a prime mover operativelyconnected through a continuously variable transmission to a propulsiondevice, propulsion-system controls, and one or more other machinesystems, the method comprising: transmitting power from the prime moverto the propulsion device with the continuously variable transmissionwhile controlling a first operating parameter of the continuouslyvariable transmission with the propulsion-system controls, includingdetermining a target adjustment for the first operating parameter basedon operator input; determining a magnitude of an adjustment limit forthe first operating parameter based on one or more second operatingparameters of the one or more other systems of the machine, includingdetermining the magnitude of the adjustment limit based at least in parton whether the machine is travelling in a forward direction or in areverse direction; and adjusting the first operating parameter based onthe target adjustment while applying the adjustment limit to the firstoperating parameter, including if a magnitude of the target adjustmentis smaller than the magnitude of the adjustment limit, adjusting thefirst operating parameter by the magnitude of the target adjustment, andif the magnitude of the target adjustment is greater than the magnitudeof the adjustment limit, adjusting the first operating parameter up tothe magnitude of the adjustment limit.